Transfer of Growth Inhibition Between Normal and Virus-Transformed Cells: Autoradiographic Studies Using Marked Cells

1967 ◽  
Vol 2 (3) ◽  
pp. 293-304
Author(s):  
M. G. P. STOKER
Keyword(s):  
Growth Inhibition ◽  
Mouse Embryo ◽  
Normal Mouse ◽  
Growth Regulation ◽  
Thymidine Incorporation ◽  
Mixed Cultures ◽  
Transformed Cells ◽  
Normal Cells ◽  
Embryo Cells ◽  
Marking Technique

[3H]Thymidine and [3H]hypoxanthine incorporation were investigated by autoradiography in mixed cultures of polyoma-transformed BHK21 cells and freshly isolated mouse fibroblasts, with ingested carbon or carmine granules as markers to distinguish the cells. An assessment of the marking technique showed that there was some exchange of granules in the mixed cultures which prevented certain identification of individual cells, but suitable criteria were chosen for distinguishing the cells on a statistical basis. Thymidine incorporation was inhibited in one third to two thirds of the transformed cells when they were in contact with stationary layers of normal cells, which themselves showed a low proportion with thymidine incorporation. Transformed cells in the same dish which were not touching the normal cells showed no inhibition of thymidine incorporation. This is in agreement with the earlier observation that growth of transformed BHK21 cells is inhibited by contact with stationary normal fibroblasts. Experiments were also carried out on hypoxanthine incorporation with the TG1 variant of polyoma-transformed cells. TG1 cells are deficient in inosinic pyrophosphorylase and autoradiography shows a failure to incorporate hypoxanthine. When TG1 cells were cultured in contact with normal mouse embryo cells, however, it was found that hypoxanthine was present in the TG1 cells as well as in the normal cells. Increased incorporation did not occur in TG1 cells in the same dish which were not in contact with normal cells. This confirms earlier observations and shows that certain substances can pass directly from normal to transformed cells. It suggests the possibility that molecules concerned in growth regulation might also be transferred directly between contiguous cells.

scholarly journals Growth Inhibition of Polyoma-Transformed Cells by Contact with Static Normal Fibroblasts

1966 ◽  
Vol 1 (3) ◽  
pp. 297-310
Author(s):  
M. G. P. STOKER ◽  
MOIRA SHEARER ◽  
C. O'NEILL
Keyword(s):  
Cell Growth ◽  
Growth Inhibition ◽  
Normal Mouse ◽  
Inhibitory Effect ◽  
Mixed Cultures ◽  
Transformed Cells ◽  
Mouse Fibroblasts ◽  
General Change ◽  
Close Proximity

The growth of polyoma-transformed BHK21 cells was studied in mixed cultures with normal mouse fibroblasts. On coverslips in excess medium, normal fibroblasts undergo one or two divisions after the cells become contiguous. Py-cell growth was not inhibited by contact with confluent fibroblasts which were still dividing, but the Py cells were rapidly inhibited after contact with fibroblasts which had become static. Further experiments confirmed the earlier view that the inhibitory effect was not due to a general change in the medium but was only brought about when cells were in contact or close proximity.

scholarly journals Loss of thrombospondin transcriptional activity in nickel-transformed cells.

1994 ◽  
Vol 14 (1) ◽  
pp. 851-858 ◽  
Author(s):  
K Salnikow ◽  
S Cosentino ◽  
C Klein ◽  
M Costa
Keyword(s):  
Chinese Hamster ◽  
Restriction Enzymes ◽  
Cell Types ◽  
Suppressor Gene ◽  
Transformed Cells ◽  
Normal Cells ◽  
Nickel Compounds ◽  
Embryo Cells ◽  
Rb Gene

mRNA from normal Chinese hamster embryo (CHE) cells was transcribed to cDNA and subtracted with an excess of mRNA from Chinese hamster embryo cells transformed by nickel compounds. Here we report the recovery of a sequence found to be highly homologous to the mouse thrombospondin 1 gene that was obtained by this subtraction procedure. Since thrombospondin is antiangiogenic, cancer cells expressing high levels of thrombospondin cannot grow in vivo because capillaries will not proliferate to cells secreting thrombospondin. To examine expression of thrombospondin, normal CHE cells were stained with monoclonal antibodies to human thrombospondin. The protein was present abundantly in the cytoplasm of normal cells but at greatly reduced levels in Ni-transformed cells. Analysis of mRNA by Northern (RNA) blot revealed transcripts in normal cells but little thrombospondin mRNA in Ni-transformed cells. Loss of thrombospondin mRNA expression was related to Ni treatment rather than transformation, since Ni-resistant cells also exhibited fewer thrombospondin transcripts than did wild-type cells. Digestion of genomic DNA with various combinations of restriction enzymes revealed thrombospondin gene patterns that were identical in both cell types, suggesting that there were no major deletions or rearrangements of the gene in the nickel-transformed cells. The inactivation of the thrombospondin gene was further investigated by analyzing the promoter activity of this gene linked to a chloramphenicol acetyltransferase (CAT) reporter plasmid that was transfected into normal and Ni-transformed cells. The CAT activity in normal cells was significantly higher than in Ni-transformed cells, suggesting that the promoter region of thrombospondin was less efficiently transcribed in Ni-transformed cells. We studied the consequences of enhanced expression of the retinoblastoma (Rb) gene, a known tumor suppressor gene, on CAT transcription driven by the human thrombospondin promoter. Cotransfection of an expression vector containing the mouse Rb gene greatly enhanced the transcription from the thrombospondin promoter such that the expression was higher in normal cells than in transformed cells.

Tumorigenicity of cells transformed by Simian virus 40 and of hybrids between such cells and normal diploid cells

1979 ◽  
Vol 36 (1) ◽  
pp. 223-240
Author(s):  
C.J. Gee ◽  
H. Harris
Keyword(s):  
Mouse Embryo ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Transformed Cells ◽  
Sv40 T Antigen ◽  
Malignant Phenotype ◽  
Embryo Cells ◽  
Diploid Cells

A number of newly isolated clonal cell lines derived from diploid mouse embryo cells transformed by SV40 were examined in vitro and in vivo. Although these lines showed the properties that define transformation in vitro, they were not tumorigenic for many passages after their initial isolation. Cells from tumours eventually produced by the SV40-transformed cells were fused with diploid mouse embryo cells. The hybrids formed were initially non-tumorigenic. This indicates that a normal diploid cell can suppress the malignant phenotype of a tumorigenic SV40-transformed cell. The hybrid cells did, however, express the SV40 T antigen and they nad a clearly transformed phenotype in vitro. It thus appears that neither the transformed phenotype nor the expression of the SV40 T antigen are enough to endow a cell with the ability to grow progressively in vivo. The relationship between the transformed phenotype and tumorigenicity was further studied by fusing malignant mouse melanoma cells with non-tumorigenic SV40-transformed cells. The hybrids expressed the transformed phenotype in vitro but unable to form tumours in vivo. The changes that occur in cells after transformation by SV40 do not apparently affect the ability of these cells to suppress the malignant phenotype of tumour cells.

scholarly journals Cell Growth Inhibition by Farnesyltransferase Inhibitors Is Mediated by Gain of Geranylgeranylated RhoB

1999 ◽  
Vol 19 (3) ◽  
pp. 1831-1840 ◽  
Author(s):  
Wei Du ◽  
Peter F. Lebowitz ◽  
George C. Prendergast
Keyword(s):  
Cell Growth ◽  
Growth Inhibition ◽  
Kinase Inhibitor ◽  
Human Tumor ◽  
Transformed Cells ◽  
Farnesyltransferase Inhibitors ◽  
Cell Growth Inhibition ◽  
Rho Proteins ◽  
Normal Cells ◽  
Drug Mechanism

ABSTRACT Recent results have shown that the ability of farnesyltransferase inhibitors (FTIs) to inhibit malignant cell transformation and Ras prenylation can be separated. We proposed previously that farnesylated Rho proteins are important targets for alternation by FTIs, based on studies of RhoB (the FTI-Rho hypothesis). Cells treated with FTIs exhibit a loss of farnesylated RhoB but a gain of geranylgeranylated RhoB (RhoB-GG), which is associated with loss of growth-promoting activity. In this study, we tested whether the gain of RhoB-GG elicited by FTI treatment was sufficient to mediate FTI-induced cell growth inhibition. In support of this hypothesis, when expressed in Ras-transformed cells RhoB-GG induced phenotypic reversion, cell growth inhibition, and activation of the cell cycle kinase inhibitor p21WAF1. RhoB-GG did not affect the phenotype or growth of normal cells. These effects were similar to FTI treatment insofar as they were all induced in transformed cells but not in normal cells. RhoB-GG did not promote anoikis of Ras-transformed cells, implying that this response to FTIs involves loss-of-function effects. Our findings corroborate the FTI-Rho hypothesis and demonstrate that gain-of-function effects on Rho are part of the drug mechanism. Gain of RhoB-GG may explain how FTIs inhibit the growth of human tumor cells that lack Ras mutations.

Interaction Between Normal and Transformed Bovine Fibroblasts in Culture

1968 ◽  
Vol 3 (4) ◽  
pp. 603-613
Author(s):  
J. PONTÉN ◽  
ELIZABETH H. MACINTYRE
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Polyoma Virus ◽  
Mixed Cultures ◽  
Transformed Cells ◽  
Normal Cells ◽  
Stationary Layer

Bovine fibroblasts transformed by polyoma virus have been cocultivated with syngeneic or allogeneic normal cells. The growth of the transformed cells was inhibited by the presence of normal cells. The strongest depression was obtained when a dense stationary layer of normal fibroblasts was challenged by polyoma cells. The inhibition was least pronounced if normal and transformed cells were simultaneously seeded. Polyoma-transformed cells were identified by radioautography after incorporation of tritiated thymidine. After 96 h of contact with stationary normal cells the number of grains per nucleus and the number of labelled nuclei had not changed indicating strong depression of DNA synthesis. A deficient attachment or premature detachment of polyoma cells could not account for the observed failure of growth in the normal/polyoma mixed cultures.

Growth inhibition of transformed cells correlates with their junctional communication with normal cells

Cell ◽  
1986 ◽  
Vol 44 (1) ◽  
pp. 187-196 ◽  
Author(s):  
Parmender P. Mehta ◽  
John S. Bertram ◽  
Werner R. Loewenstein
Keyword(s):  
Growth Inhibition ◽  
Transformed Cells ◽  
Normal Cells ◽  
Junctional Communication

Loss of thrombospondin transcriptional activity in nickel-transformed cells

1994 ◽  
Vol 14 (1) ◽  
pp. 851-858
Author(s):  
K Salnikow ◽  
S Cosentino ◽  
C Klein ◽  
M Costa
Keyword(s):  
Chinese Hamster ◽  
Restriction Enzymes ◽  
Cell Types ◽  
Suppressor Gene ◽  
Transformed Cells ◽  
Normal Cells ◽  
Nickel Compounds ◽  
Embryo Cells ◽  
Rb Gene

mRNA from normal Chinese hamster embryo (CHE) cells was transcribed to cDNA and subtracted with an excess of mRNA from Chinese hamster embryo cells transformed by nickel compounds. Here we report the recovery of a sequence found to be highly homologous to the mouse thrombospondin 1 gene that was obtained by this subtraction procedure. Since thrombospondin is antiangiogenic, cancer cells expressing high levels of thrombospondin cannot grow in vivo because capillaries will not proliferate to cells secreting thrombospondin. To examine expression of thrombospondin, normal CHE cells were stained with monoclonal antibodies to human thrombospondin. The protein was present abundantly in the cytoplasm of normal cells but at greatly reduced levels in Ni-transformed cells. Analysis of mRNA by Northern (RNA) blot revealed transcripts in normal cells but little thrombospondin mRNA in Ni-transformed cells. Loss of thrombospondin mRNA expression was related to Ni treatment rather than transformation, since Ni-resistant cells also exhibited fewer thrombospondin transcripts than did wild-type cells. Digestion of genomic DNA with various combinations of restriction enzymes revealed thrombospondin gene patterns that were identical in both cell types, suggesting that there were no major deletions or rearrangements of the gene in the nickel-transformed cells. The inactivation of the thrombospondin gene was further investigated by analyzing the promoter activity of this gene linked to a chloramphenicol acetyltransferase (CAT) reporter plasmid that was transfected into normal and Ni-transformed cells. The CAT activity in normal cells was significantly higher than in Ni-transformed cells, suggesting that the promoter region of thrombospondin was less efficiently transcribed in Ni-transformed cells. We studied the consequences of enhanced expression of the retinoblastoma (Rb) gene, a known tumor suppressor gene, on CAT transcription driven by the human thrombospondin promoter. Cotransfection of an expression vector containing the mouse Rb gene greatly enhanced the transcription from the thrombospondin promoter such that the expression was higher in normal cells than in transformed cells.

scholarly journals Scanning electron microscopy of in vitro chemically transformed mouse embryo cells.

1976 ◽  
Vol 68 (3) ◽  
pp. 654-664 ◽  
Author(s):  
L E Malick ◽  
R Langenbach
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mouse Embryo ◽  
Control Cell ◽  
Surface Characteristics ◽  
Transformed Cells ◽  
C3h Mice ◽  
Embryo Cells ◽  
Scanning Electron

A cloned nontumorigenic control cell line of C3H mouse embryo cells (C3H/1OT1/2CL8) and two cell lines derived from it by treatment in vitro with 7,12-dimethylbenz(a)anthracene (DMBA) or 3-methylcholanthrene (MCA) were studied by scanning electron microscopy. Confluent control cells were polygonal in shape and extensively flattened with smooth surfaces. Both in vitro transformants were pleomorphic to fusiform in shape, thicker than the control cells, and lacked contact inhibition. Microvilli of variable length and small marginal ruffles were characteristic surface alterations of the MCA-transformed cells, while blebs and numerous cytoplasmic strands extending between cells were typical of the DMBA transformant. Inoculation of the DMBA-transformed cells into C3H mice and re-establishment of cells from one of the subsequent fibrosarcomas in culture revealed an increased number of microvilli on the surface of the cells and an alteration in growth pattern. Other surface characteristics remained the same. A possible relationship between surface topography and outer membrane glycolipids is discussed.

Spontaneous Production of Type C Virus Particles in a Culture Derived from Rat Embryo Cells

1972 ◽  
Vol 30 ◽  
pp. 288-289
Author(s):  
Elizabeth S. Priori ◽  
T. Shigematsu ◽  
B. Myers ◽  
L. Dmochowski
Keyword(s):  
Virus Particle ◽  
Mouse Embryo ◽  
Calf Serum ◽  
Embryo Cell ◽  
Virus Particles ◽  
Extracellular Virus ◽  
Mouse Embryo Cell ◽  
Mature Virus Particle ◽  
Embryo Cells ◽  
Type C

Spontaneous release of type C virus particles in long-term cultures of mouse embryo cells as well as induction of similar particles in mouse embryo cell cultures with IUDR or BUDR have been reported. The presence of type C virus particles in cultures of normal rat embryos has not been reported.NB-1, a culture derived from embryos of a New Zealand Black (NB) rat (rats obtained from Mr. Samuel M. Poiley, N.C.I., Bethesda, Md.) and grown in McCoy's 5A medium supplemented with 20% fetal calf serum was passaged weekly. Extracellular virus particles similar to murine leukemia particles appeared in the 22nd subculture. General appearance of cells in passage 23 is shown in Fig. 1. Two budding figures and one immature type C virus particle may be seen in Fig. 2. The virus particles and budding were present in all further passages examined (currently passage 39). Various stages of budding are shown in Figs. 3a,b,c,d. Appearance of a mature virus particle is shown in Fig. 4.

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